Process of preparing 8-alkyl unsymmetrical carbocyanine dyes



March 4, 1941- G. s. BRooKx-:R x-:TAL 2,233,510

PROCESS OF PREPARING S-ALKYL UNSYMMETRICAL CRBOCYANINE DYES Filed Sept. 14, 1937 Les/ie 6.5. Brooker Frank L W/z/'te ISY da L) ATTOR "YS Patented Mar. 4, 1941 uNlTlazo` STATES PROCES'SOF PREPARING S-ALKYL NSYM- METRIUAL C'ARBOCYANINE DYES Leslie G; ester, pany., Rochester, N.- Jersey S: Brookerand Frank L. White, Roch- N. Y., assignors to Eastman Kodak Com- Y., a corporation of New Application September'li, 1937, Serial No. 163,781

4 Claims.

wherein A represents a divalentl organic group, such as a phenyl'eneA or'naphthylene group, A represents an ethylene group, R, R and R represent alkyl-groups, X represents anv acid radical and Y represents a divalent atom of' the `oxygen group of elements, such as sulfur or selenium for example. More particularly,"-A represents an ethylene group, such as- -CH-CH2-, methylethylene or phenyletliylenefor example; A represents aV phenylenel group, such asv CeH4-, methylphenylene, phenyl phenylene, chlorophenylene, aminophenyleneor' alkoxyphenylenefor example or A represents a naphthylene group, such asa-naphthylene yor -naphthyl'enefor naphthylenegroupscarrying simple substituents, such as alkyl, chloro, alkoxy, aminoor" the likefor example; R, R and R represent alkyl groups, such as methyl, ethyl, isopropyl, n-butyl, iso-amyl, secamyl, n-d'ecyl-*or allyl for exampl'eiand'X represents an acid radical, such asr halide, toluenesulfonate, -alkylsulfate or perchlorate for example. Our new" dyes canbeca'lled 8-alkylthiathiazolinocarbocyanine dyes, 8-alkylselenathiazolinocarbocyaninev dyes, etc.

Our new dyes can be ketone compound ofthe prepared bylreacting a.

following formula t A( l? R wherein A, R,` R" andY havethe values set forth under. Formula I above, with a. thiazoline quater- 55 nary salt containing'a reactive alkyl group, e. g. a reactive methyl group, in the alpha or 2posi tion. The reactions can be eected by merely heating the ketone compound and Quaternary salt together. We. have found .it/advantageous to oo-.effect'the reactionslin thev presence oi.v a Waterbinding agent. We have found that anhydrides of lower fatty acids', such as anhydrides of acetic, propionic or` butyric acids for example, are advantageously employed. Diluents can be employed in the reaction mixture. Heat accelerates the formation of our new dyes.

While the process for preparing our new dyes is subject to variation, particularly as respects: the nature and quantity Vof ketone compound employed, the nature and quantity of thiazoline Quaternary salt employed, the nature and quantity of water-binding agent employed if any, the nature and quantity of diluent employed if any, the temperatures employed, the time of reaction. and the method of isolation and purification of the dyes, the following examples will serve to illustrate the manner of obtaining our new dyes. These examples are not intended to limit our invention.

EXAMPLE l.-8-ethyl-2,3dimethylthiathiaeolinocarbocyanine iodide 4.38 g. (1 mol.) Vof'2-methy1-1-propionylmethyl ene-benzothiazoline and 5.74 g. (1 mol.) of 2- methylthiazoline metho-p-toluenesulfonate Were heated in about 15 cc. of proponic anhydride at reiiuxing temperature for about 15 minutes. The separation of the dye from the reaction mixture was facilitatedfby the addition of 200 ce. of diethyl ether to the cooled reaction mixture, followed by chilling at C. for several hours. The ether-propionic anhydride layer was decanted. The oily residue was dissolved in hot methyl alcohol (5 cc.) and the dye was converted to the iodide by the addition of a hot aqueous solution of potassium iodide. Upon cooling, the dyeiodide separated. It was ltered, washed with water and boiled with acetone.` After two rel crystallizations from 95% ethyl alcohol, the dye was obtained as brownish-orange crystals, melting at 258 to 260 C. with decomposition. The dye has the following formula:

CH3 CH3 \I EXAMPLE 2. 2,3'-diethyl-S-methylselenathiaeolinocarbocyam'ne iodide 5.32 g. (1 mol.) of l-acetylmethyl-2-ethylbenzoselenazoline and 6.02 g. (1 mol.) of 2- methylthiazoline eth0-p-toluene-sulfonate were heated in about cc. of propionie anhydride at reuxing temperature for about 6 minutes. The dye was isolated from the reaction mixture and converted to the iodide 'as in Example 1. After tworecrystallizations from methyl alcohol, the

C zHs dye was obtainedlasdull reddish. crystals, melt-l ing at 251 to 252 C. with decomposition. dye has the following formula:

-naphthothiazoline and 6.02 g. (1 mol.) of 2- methylthiazoline etho-p-toluenesulfonate were The - heated in about 15 cc. of propionic anhydride at refluxing temperature for about 15 minutes. The dye was isolated and converted to the iodide as in Example 1. After two recrystallizations from ethyl alcohol, the dye was obtained as dull EXAMPLE 4.-8ethyl-2,3-dimethyl-3,4 benzothz'- athiazolinocarbocydm'ne iodide 5.38 g. (1 mol.) of 1-methyl-2-propionylmethylene--naphthothiazoline and 5.74 g. (1 mol.)

, of Z-methylthiazoline metho-p-toluenesulfonate` were heated in about 15 cc. of propionic anhydrde for about 20 minutes at refluxing temperature. The dye was isolated and converted to the iodide as in Example 1. After two recrystallizations, the dye was obtained as dark brownish crystals melting at 231 to 232 C. with decomposition. The dye has the following formula:

Exile/[PLE 5.-2,3-diethyl-S-methylthiathideolinocarbocyanine iodide 2.19 g. (1 mol.) of 1-acetylmethylene-2-ethyl-i benzothiazoline and,3.0l g. (1 mol.) of 2-methylithiazoline etho-p-toluenesulfonate were heated in about 10 cc. of acetic anhydride for about 10 minutes at refluxing temperature. The dye was isolated and converted to the iodide as in Example 1. After two recrystallizations from methyl alcohol, the dye was obtained as minute reddish crystals melting at 228 to 230 C. with decomposition. The dye has the following formula:

GH: 1,\ 7 -s 9 :von \1o=oH-c=oH-c2'/ @H2 l 2 ,s/ \,3./

02H5 02H5 I In preparing our new dyes, we have foundit advantageous to employ the thiazoline toluenesulfonates. Since the dye-toluenesulfonates were fairly soluble, it is advantageous to isolate the dyes as *the iodides with potassium iodide. The dyes can similarly be conveniently' isolated as the bromides or perchlorates with potassium bromide or sodium perchlorate.

The ketone compounds employed in our process can be prepared by reacting an appropriate cyclicammonium quaternary salt containing a reactive alkyl group with an acyl halide in the presence of an acid-binding agent. Pyridine is advantageously employed as the acid-binding agent. For example, to prepare 1-acetylmethylene-2- ethylbenzothiazoline, one molecular proportion of l-methylbenzothiazole ethiodide can be reacted with acetyl chloride in the presence of pyridine. The process for preparing the ketone compounds is fully described in British Patent 466,269. lacetylmethy1ene2 ethylbenzothiazoline can also b e called l-acetonylidene-Z-ethylbenzothiazoline.

The thazoline toluenesulfonates employed in the above examples can be prepared as set forth in the following examples:

(1 mol.) of methyl-p-toluenesulfonate were heated at C. for about 90 hours. The resulting crude product was employed without further purification.

EXAMPLE '7.-2-methylthazolz'1'ze etho-p-toluenesulfonate 2.02 g. (l mol.) of 2-methylthiazoline and 4.00l

g. (1 mol.) of ethyl-p-toluenesulfonate were heated together at to 110 C. for about 100 hours. The resulting crude product was used without further purification. Y

We have found it advantageous to employ one molecular proportion of the thiazoline quaternary salt to reactwith one molecular proportion of the ketone compound. However, an excess of either can be employed.v Our ynew unsymmetrical dyes give rise to photographic emulsions possessing novel green speeds when incorporated; in lthe emulsions. By means of our new dyes, emulsions sensitized in a novel manner to light of wavelengths-between about 515 muto about 550 mu can be prepared. Our` invention is particularly directed to the customarily employed gelatino-silver-halide emulsions.

rier is other than gelatin, for example, a resinous substance or cellulosic derivative which has substantially no deleterious effect on the light-sensitive materials. include such emulsions as are commonly em ployed in the art, for example, silver chloride or silver bromide emulsions which can contain other salts which may be light-sensitive. By way of illustration, the herein-described Ysensitized photographic emulsions wereprepared employing ordinary gelatine-silver-bromide emulsions.

In the preparation of photographic emulsions containing our new unsymmetrical dyes, it is only necessary to disperse the dyes in the emulsions. The method-s of incorporating dyes in emulsions are simple and well known to those skilledY inthe art..` Inpracticing our inventionv it is convenient vto add the dyes from their solutionsn in appropriate solvents. The solvent must, y of course, belcompatible with theemulsion, sub- 1 stantially free from any deleterious eifect on `the materials and capableofdissolvlight-Sensitive ing thedyes.A y Methanol has jproven satisfactory as a solvent for our new dyes.H The" dyes are However,v our new unsymmetricalV dyes I can `be employed in emulsions inv which the car-'- As silver halide emulsions,v weA advantageously incorporated in the finished, Washed emulsion and should be uniformly distributed throughout to secure the best results.

The concentration of our new unsymmetrical dyes in the emulsions can vary widely, e. g. from about to about 100 mg. per liter of lowable emulsion, The concentration of the dye will vary according to the type of light-sensitive material in the emulsion and according to the effects desired. The suitable and most `economical concentration for any given emulsion will be apparent to those skilled in the art, upon making the ordinary tests and observations customarily used in the art .of emulsion making. To prepare a geiatino-silVer-halide emulsion, the following procedure is satisfactory: A quantity of the dye is dissolved in methyl alcoho-l or acetone and a volume .of this solution (which may be diluted with water) containing from 5 to 100 mg. of dye is slowly added to about 1000 cc. of a ilowable gelatino-silver-halide emulsion with stirring. Stirring is continued until the dye is uniformly and practically homogeneously dispersed. Ordinarily to 20 mg. of dye per 1000 cc. of ilowable emulsion willsuliice to produce the maximum sensitizing eiect with the ordinary gelatine-silver-halide emulsions. The above statements are only illustrative and not to be understood as limiting our invention in any sense, as it will be apparent that our dyes can be incorporated by .other methods in many of the photographic emulsions customarily employed in the art, such, for instance, as by bathing the plate or nlm, upon which the emulsion has been coated, in a solution of the dye in an appropriate solvent, although such a method is ordinarily not to be preferred. The claims are intended to cover any combination of these new dyes with a photographic silver halide emulsion, whereby the dye exerts a sensitizing effect upon the emulsions, as well as a photographic element comprising a support, ordinarily transparent, upon which the light-sensitive emulsion is coated or spread and allowed to dry.

The accompanying drawing is by way of illustration and depicts the sensitivity o-f emulsions containing four of our new dyes. Each ligure in the drawing is a diagrammatic reproduction of a spec-trogram showing the sensitivity of a silver bromide emulsion containing one of our new dyes.

In Fig. 1,the sensitivity of an ordinary gelatinesilver-bromide emulsion containing 8-ethyl-2,3 dimethylthiathiazolinocarbocyanine iodide is depicted. Maximum sensitivity is in the green at about 515 mu and the extra sensitivity conferred by the dye extends to nearly 600 mu.

In Fig. 2, the sensitivity of an ordinary gelatino-silver-brom-ide emulsion containing 2,3- diethyl 8 methylselenathiazolinocarbocyanine iodide is depicted. Maximum sensitivity is in the green at about 530 mu and the extra sensitivity conferred by the dye extends to beyond 600 mu.

In Fig. 3, the sensitivity of an ordinary gelatine-silver bromide emulsion containing 2,3- diethyl 8 methyl-3,4-benzothiathiazolinocarbocyanine iodide is depicted. Maximum sensitivity is in the green at about 540 mu and the extra sensitivity conferred by the dye extends to beyond 600 mu.

In Fig. 4, the sensitivity of an ordinary gelatino-silver-bromide emulsion containing 8- alkyl groups.

ethyl 2,3' dimethyl-3,4-benzothiathiazolinocarbocyanine `iodide is depicted. Maximum sensitivity is in .the lgreen at about 535 mu and the extra sensitivity conferred by the dye extends to about 600 mu.

Still further examples illustrating our invene tion could be cited, but the foregoing will be suilicient to teach those skilled in the art the manner in which our invention is carried out.

What we claim as our invention and desire to be secured by Letters Patent of the United States is:

1. A process for preparing a dye comprising reacting, inthe presence of a water-binding agent, a Z-methylthiazoline Quaternary salt with a ketone compound of the following formula:

wherein A represents an organic gro-up selected from the group consisting of phenylene and naphthylene groups, Y represents a divalent atom selected from the group consisting of sulfur and selenium and R and R" represent alkyl groups.

2, A process for preparing a dye comprising reacting, in the presence of a water-binding agent, a 2-methylthiazoline quaternary sallt with a ketone compound of the following formula:`

wherein A represents an organic -group selected from the group consisting of phenylene and naphthylene groups and R and R represent alkyl groups.

3. A p-rocess for preparing a dye comprising reacting, in the presence of propionic anhydride water-binding agent, a Z-methylthiazoline alkylp-toluenesulfonate with a ketone compound of the following formula:

wherein A represents an organic group selected from the group consisting of phenylene and naphthylene groups and R and R represent alkyl groups.

4. A process for preparing a dye comprising reacting, in the presence of a water-binding agent, a 2-methylthiazoline alkyl-p-toluenesulfonate with a ketone compound of the followingformula:

wherein A represents an organic group selected from the group consisting of phenylene and naphthylene groups and R and R represent LESLIE G. S. BROOKER. FRANK L. WHITE. 

